Not Applicable
Not Applicable
Not Applicable
1. Field of the Invention
The invention provides a method for realizing a highly compact system for determining the position of a movable part for selectively closing or releasing an opening, in particular the panel of a sliding roof or a motor-driven window in a door of a motorcar or truck, in respect of which it is important to know the position of the roof panel in order to, for instance, cause the panel to stop at a particular location.
2. Description of the Related Art
Devices are known which comprise external sensors such as Hall-effect sensors, disposed at a magnet with one or more pairs of poles which is/are mounted around the motor shaft or on a shaft connected to the motor shaft. Also, devices are known which comprise external sensors such as optical slotted sensors operated by crenellations, which are again mounted on or against a wheel driven, with or without a transmission, by the motor shaft. The motor can move the roof panel for instance via a drive cable. Via this drive cable, the wheel with the crenellations can again be driven.
The drawback of such systems is that if gear wheels are involved, they usually turn out to be large.
The invention enables the use of several wheels, which nevertheless do not occupy more space than the space occupied by one wheel. In particular if the building-in space is limited, this will be highly advantageous.
For determining the position, a gear wheel driven by the drive cable is used, which gear wheel drives, by means of an eccentric, a second wheel having substantially the same center as the first one. As a result, this second wheel rotates far more slowly than the first wheel.
Mounted on a ring on the first wheel are crenellations rotating through an optical slotted sensor whereby incremental position information is provided.
On a concentric second ring on the first wheel, a crenellation is arranged. This crenellation also rotates through a slotted sensor, which produces a reference pulse which, however, occurs several times over the entire distance. On the second gear wheel, too, a crenellation is arranged. By means of a slotted sensor, this crenellation is scanned, too. Together with the reference pulse from the sensor around the second ring of the first wheel, an unequivocal, accurate reference pulse can now be made.
A combination of two gear wheels always takes up much more space than one gear wheel.
The invention has the advantage of two gear wheels, i.e. a large number of distance pulses with an accurate reference pulse, and the space occupation of one gear wheel. In particular in places where there is little space for a control, this invention will be highly advantageous.